The Witches isn't a particularly tough book to follow. There aren't any plot twists, confusing characters, or philosophically deep thoughts. Everything's pretty straightforward, and the book even has illustrations. There's just one problem for American readers: Roald Dahl grew up in England. Well, that's not a problem in itself (except that he probably missed out on hot dogs as a kid), but it definitely makes for some interesting words.
Want some examples? Of course you do. He calls head lice "nits" (6.9), the elevator a "lift" (18.10), and, the most confusing of all for Americans, "football" (9.18) means soccer. Let's not forget the spelling, too: "favourite" (4.17) and "marvellous" (18.31) come to mind.
Luckily, because Roald Dahl likes to use made-up words anyway, these British terms don't get in the way too much. We're more stumped by fantabulous (8.16), tomfiddling (8.37), frumptious (8.55), and blabbersnitch (9.39), to name a few Dahl-isms. Wait, though! Get this: tuppenny-ha'penny (8.27) is a real word! We swear. Good luck pronouncing it, though. In any case, all of these words are pretty easy to figure out in context. It's just a matter of not getting stuck on them. The rest is a smooth ride.